In telecommunication switching systems comprising a plurality of switching nodes, a path being set up through the switching nodes may double back on itself. For example, a first switching node may route a call to a second switching node on the basis of a dialed telephone number and have the second switching node reroute the call back to the first switching node upon the determination that the dialed telephone number does not specify a telephone station set on the second switching node. The second switching node determines that the dialed telephone station set is connected to a third switching node and that the third switching node can only be reached from the second switching node by going through the first switching node. The result is that two communication paths are utilized by the call between the first switching node and the second switching node. This is highly undesirable since it utilizes two communication paths where none are required.
This problem has not arisen in prior art telecommunication switching systems because these systems have always used a fixed dialing plan with fixed telecommunication routes between each of the switching nodes. However, the problem does arise where the dialing plan hierarchy and the switching node hierarchy are not known to the switching nodes at the time of initialization; and the switching nodes must immediately determine routes through the telecommunication system.
It is known in the art for a switching node to send back a release message to the originating switching node. The function of a release message, however, is to tear down the entire path back to the originating switching node. The problem just described, however, is one of simply backing the call back from the second switching node to the first switching node and advising the first switching node to route the call to another switching node.
In addition, it is known in telecommunication systems to transmit a lookahead message to an automatic call distribution system or switching node to determine if that entity has the capability to handle the call. However, the lookahead technique requires transmission of two messages. One to the destination switching node and one back from the destination switching node. In addition, the lookahead message provides no information with respect to where the call should be routed to if the potential destination switching node is not capable of handling the call.
There exists a need in the art for a mechanism or message that can be used to back a call back to a transmitting switching node from receiving switching node and to supply information that will allow the transmitting switching node to route the call to a new switching node.